What is the IRS 1040-X Form?

Updated for Tax Year 2021 • January 19, 2022 03:34 PM


If you ever discover an error on a tax return, realize you qualify for deductions or credits you didn't take, or forgot to include some income, you may be able to amend your return by filing a Form 1040-X. When you prepare the 1040-X, it's not necessary to complete a brand new tax return. Form 1040-X only requires that you update the numbers that will change.

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When you can file

You can amend your taxes as long as your original tax return was prepared using Forms

  • 1040,
  • 1040-SR,
  • 1040A,
  • 1040EZ,
  • 1040EZ-T,
  • 1040NR or
  • 1040NR-EZ.

If your changes affect more than one tax return, you must file a separate Form 1040-X for each tax year. Since it may be necessary to prepare additional forms or schedules, be sure you use the ones required for that specific tax year.

How you can benefit

When you use Form 1040-X to claim additional deductions or credits or to correct an error that reduces the amount of tax you owe for that year, the Form 1040-X serves as your formal claim for a refund. Additionally, many small business owners can use the form to carry back net operating losses that occur in one of the subsequent two tax years. The IRS notes that it takes approximately eight to twelve weeks to process amendments, so be on the lookout for your refund after this time.

Information you need

The most helpful document you need when preparing Form 1040-X is a copy of the original tax return you’re amending. You can transfer some of the original information onto the amended tax return, such as

You also need any documentation that relates to your changes. This can be a number of items such as proof of payment for a new deduction you are claiming or an additional W-2 for additional income you need to report.

If you attached any schedules to the original return, you don't need to complete these again unless your amendments cause the numbers on it to change.

Time limitations for filing

The IRS limits the amount of time you have to file an amended tax return. For most taxpayers, it must be done either

  • within three years of the original filing deadline, or
  • within two years of actually paying the tax for that year.

However, if you filed the original return after the deadline because you obtained an extension of time to file, then the three-year period begins on the date you actually filed it. Some people who are disabled or otherwise incapacitated may have more than three years, depending on the circumstances.

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